The present invention relates in general to time locks for bank vaults and safes and similar timed high security devices for security receptacles, and more particularly to the carrier structure of manually settable time locks providing means for releasibly holding the carrier against accidental or vibrational lateral movement toward its unlocking position releasing a lever or similar actuator to unlock the time lock and which releases the carrier to undergo unlocking movement when the timing mechanism times down to zero.
Heretofore, time locks have been in common, widespread use to place bank vaults and similar safes, security spaces, and the like in a lock-out condition rendering them disabled from being opened in the normal way by bank personnel, as by proper dialing of a combination lock, during certain chosen times, such as between the bank closing time one day and its opening time the next banking day. In recent years, these time locks have customarily involved a box or case having two or three timer units or clockwork movements, to provide backup redundancy in case one or two of the timer units fail, each of which has a settable dial graduated in hours and set from a key insertable into openings in the time lock case to indicate the desired locking hours or time lapse between setting of the timer and the time of opening of the vault the next working day. Each timer unit or movement customarily has a main spring and gear system to concurrently wind the main drive spring for the clockwork mechanism and drive the dial in a wind-up or increasing time lapse direction relative to a stationary pointer or index mark, and the dial usually has a trip pin or stub fixed on the dial face to engage an abutment surface on the end of one of a plurality of rigid arms extending from a transversely movable carrier when the associated timer unit dial times out to zero time and move the carrier to a release position allowing a snubber bar connected in the usual manner to the bolts for the vault door, as by connection to a common control bar for the bolts to retract to unlocking position. Alternatively, a snap action trip arm mechanism may be provided with each timer unit to abruptly kick the carrier toward release position at zero time, as disclosed in U.S. patent application Ser. No. 940,834 filed Sept. 7, 1978 by Charles G. Bechtiger et al, owned by the assignee of the present application. The carrier typically has three of such rigid arms extending to abutment ends located at the zero time positions for the trip pins of each of the three dials of the three timer units, so that any one of the three trip pins when it engages the abutment end surface of the associated extension arm of the carrier will push the carrier toward its release position by the force of the stored energy in the associated main drive spring to unlock the time lock.
The carrier is usually only spring biased to locking position and typically moves only a short distance transversely of the time lock to effect release of the time lock, usually by withdrawing a small abutment surface bounding a slot from holding position relative to a notch or shoulder of a push lever or actuator accessible from the front of the time lock case and allowing a blocking member to drop from blocking relation to a snubber bar connected to the vault door bolts. It is possible that vibration of the time lock mechanism from various sources could cause sufficient movement of the carrier toward release position against the spring bias of the usual carrier retaining spring to effect accidental or surreptitious release of the time lock. Sidewise accelerations issuing for instance from external shocks can exert a force onto the carrier plate in the direction of making it open the lock. A force acting in a direction toward the release position of the carrier, or to the right as viewed in FIGS. 2 and 7 of this application may overcome the retaining action of the carrier retaining spring. The main carrier plate must be strong and therefore massive because of functional requirements. The retaining spring cannot be made very strong in order not to overload the timing mechanisms when releasing. The ratio of carrier mass to retaining spring force is therefore high and cannot be reduced below a limit given by considerations of design and proper functioning. Therefore, there exists always a force of relatively small value sufficient to shift the carrier plate in the opening direction.
An object of the present invention is the provision of a novel carrier mechanism for time locks designed to overcome the above-described problem, wherein a deadbolt latch lever is provided on the carrier which is latched against a stop shoulder when the timer mechanisms are above zero time condition and is released to allow the carrier of the time lock to shift to release position when the dial times down to zero time.
Another object of the present invention is the provision of a novel carrier mechanism for time locks as described in the immediately preceding paragraph, wherein a slide plate parallels and is slidable relative to the carrier and includes means for swinging the latch lever between carrier latching position and carrier release position when the slide plate is moved between a normal and a displaced position, and the slide plate includes abutments to be engaged by the trip mechanism of the timer units immediately prior to engagement of the carrier to move the latch lever to release position.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings showing a preferred embodiment of the invention.